This invention relates to the catalytic treatment of waxy feeds including slack wax, Fischer-Tropsch wax, waxy raffinates and waxy distillates to produce a high quality lube oil product having a unique structural character, a low pour point and viscosity, and a high viscosity index (VI).
The isomerization of wax and waxy feeds to liquid products boiling in the lube oil boiling range and catalysts useful in such practice are well known in the literature. Preferred catalysts in general comprise noble Group VIII metals on halogenated refractory metal oxide support, e.g. platinum on fluorided alumina. Other useful catalysts can include noble Group VIII metals on refractory metal oxide support such as silica/alumina which has their acidity controlled by use of dopants such as yttria. As useful as isomerization processes may be, in general they do not improve the pour point of the feed subjected to isomerization.
Catalytic dewaxing is also a process well documented in the literature. As is known, catalytic dewaxing generally leads to lubes with low pour point; however, the VI also tends to be lower as a result of such processing.
Extensive investigations have been conducted in an effort to develop new and improved catalysts and processing schemes for preparing high quality lubes having a low pour point and a high VI.
It has now been discovered that waxy feeds such as those containing greater than 50 wt % wax can be treated so as to produce a lube oil product having a unique structural character, excellent low temperature properties and a high VI. The invention relates to a method for producing a lube basestock from a feed containing 50 wt % or more of wax comprising:
(a) hydrotreating the feed under hydrotreating conditions so as to reduce the sulfur and nitrogen content thereof;
(b) hydroisomerizing at least a portion of the hydrotreated feed under hydroisomerization conditions to reduce the wax content in the feed to less than about 40 wt %;
(c) separating the hydroisomerizated feed of step (b) to obtain a lube fraction boiling above about 340xc2x0 C.;
(d) processing at least a portion of the lube fraction of step (c) under hydrocatalytic dewaxing conditions with a catalyst comprising at least one active metal hydrogenation component on a dewaxing catalyst and at least one active metal hydrogenation component on an amorphous hydroisomerization catalyst.
Another embodiment of the invention comprises a method for producing a lube basestock from a feed containing 50 wt % or more of wax comprising:
(a) hydrotreating waxy feed under hydrotreating conditions sufficient to reduce the sulfur and nitrogen content thereof to produce a hydrotreated feed;
(b) hydroisomerizing at least a portion of the hydrotreated feed under hydroisomerization conditions sufficient to reduce the wax content in the feed to about 35 wt % or less;
(c) separating the hydroisomerized feed of step (b) to obtain a lube fraction boiling above about 340xc2x0 C.;
(d) solvent dewaxing the lube fraction to a pour point of from about +10xc2x0 C. to about xe2x88x9220xc2x0 C. to obtain a dewaxed feed;
(e) processing at least a portion of the dewaxed feed under hydro-catalytic dewaxing conditions with a unitized powder pellet catalyst comprising at least one active metal component on a 10 member ring unidirectional pore inorganic oxide molecular sieve and at least one active metal component on an isomerization component selected from refractory metal oxides and refractory metal oxides including a dopant.
Importantly, the processes of the present invention provides high yield of basestock based on feed.
These and other embodiments of the invention will be discussed below.